From b4416f58d54bec73aeefa3122fb195ab1dd73517 Mon Sep 17 00:00:00 2001
From: Justin Bogner <mail@justinbogner.com>
Date: Tue, 18 Mar 2014 21:58:06 +0000
Subject: CodeGen: Include a function hash in instrumentation based profiling

The hash itself is still the number of counters, which isn't all that
useful, but this separates the API changes from the actual
implementation of the hash and will make it easier to transition to
the ProfileData library once it's implemented.

llvm-svn: 204186
---
 clang/lib/CodeGen/CodeGenPGO.cpp | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

(limited to 'clang/lib/CodeGen/CodeGenPGO.cpp')

diff --git a/clang/lib/CodeGen/CodeGenPGO.cpp b/clang/lib/CodeGen/CodeGenPGO.cpp
index 207cb665b0f..1f2fe38c40e 100644
--- a/clang/lib/CodeGen/CodeGenPGO.cpp
+++ b/clang/lib/CodeGen/CodeGenPGO.cpp
@@ -58,10 +58,15 @@ PGOProfileData::PGOProfileData(CodeGenModule &CGM, std::string Path)
       ReportBadPGOData(CGM, "pgo data file has malformed function entry");
       return;
     }
-    while (*--CurPtr != ' ')
-      ;
     StringRef FuncName(FuncStart, CurPtr - FuncStart);
 
+    // Skip over the function hash.
+    CurPtr = strchr(++CurPtr, '\n');
+    if (!CurPtr) {
+      ReportBadPGOData(CGM, "pgo data file is missing the function hash");
+      return;
+    }
+
     // Read the number of counters.
     char *EndPtr;
     unsigned NumCounters = strtol(++CurPtr, &EndPtr, 10);
@@ -99,7 +104,7 @@ PGOProfileData::PGOProfileData(CodeGenModule &CGM, std::string Path)
   MaxFunctionCount = MaxCount;
 }
 
-bool PGOProfileData::getFunctionCounts(StringRef FuncName,
+bool PGOProfileData::getFunctionCounts(StringRef FuncName, uint64_t &FuncHash,
                                        std::vector<uint64_t> &Counts) {
   // Find the relevant section of the pgo-data file.
   llvm::StringMap<unsigned>::const_iterator OffsetIter =
@@ -111,11 +116,15 @@ bool PGOProfileData::getFunctionCounts(StringRef FuncName,
   // Skip over the function name.
   CurPtr = strchr(CurPtr, '\n');
   assert(CurPtr && "pgo-data has corrupted function entry");
-  while (*--CurPtr != ' ')
-    ;
 
-  // Read the number of counters.
   char *EndPtr;
+  // Read the function hash.
+  FuncHash = strtoll(++CurPtr, &EndPtr, 10);
+  assert(EndPtr != CurPtr && *EndPtr == '\n' &&
+         "pgo-data file has corrupted function hash");
+  CurPtr = EndPtr;
+
+  // Read the number of counters.
   unsigned NumCounters = strtol(++CurPtr, &EndPtr, 10);
   assert(EndPtr != CurPtr && *EndPtr == '\n' && NumCounters > 0 &&
          "pgo-data file has corrupted number of counters");
@@ -246,15 +255,17 @@ llvm::GlobalVariable *CodeGenPGO::buildDataVar() {
 
   // Create data variable.
   auto *Int32Ty = llvm::Type::getInt32Ty(Ctx);
+  auto *Int64Ty = llvm::Type::getInt64Ty(Ctx);
   auto *Int8PtrTy = llvm::Type::getInt8PtrTy(Ctx);
   auto *Int64PtrTy = llvm::Type::getInt64PtrTy(Ctx);
   llvm::Type *DataTypes[] = {
-    Int32Ty, Int32Ty, Int8PtrTy, Int64PtrTy
+    Int32Ty, Int32Ty, Int64Ty, Int8PtrTy, Int64PtrTy
   };
   auto *DataTy = llvm::StructType::get(Ctx, makeArrayRef(DataTypes));
   llvm::Constant *DataVals[] = {
     llvm::ConstantInt::get(Int32Ty, getFuncName().size()),
     llvm::ConstantInt::get(Int32Ty, NumRegionCounters),
+    llvm::ConstantInt::get(Int64Ty, FunctionHash),
     llvm::ConstantExpr::getBitCast(Name, Int8PtrTy),
     llvm::ConstantExpr::getBitCast(RegionCounters, Int64PtrTy)
   };
@@ -847,6 +858,8 @@ void CodeGenPGO::mapRegionCounters(const Decl *D) {
   else if (const BlockDecl *BD = dyn_cast_or_null<BlockDecl>(D))
     Walker.VisitBlockDecl(BD);
   NumRegionCounters = Walker.NextCounter;
+  // FIXME: The number of counters isn't sufficient for the hash
+  FunctionHash = NumRegionCounters;
 }
 
 void CodeGenPGO::computeRegionCounts(const Decl *D) {
@@ -905,8 +918,9 @@ void CodeGenPGO::loadRegionCounts(PGOProfileData *PGOData) {
   // ignore counts when the input changes in various ways, e.g., by comparing a
   // hash value based on some characteristics of the input.
   RegionCounts = new std::vector<uint64_t>();
-  if (PGOData->getFunctionCounts(getFuncName(), *RegionCounts) ||
-      RegionCounts->size() != NumRegionCounters) {
+  uint64_t Hash;
+  if (PGOData->getFunctionCounts(getFuncName(), Hash, *RegionCounts) ||
+      Hash != FunctionHash || RegionCounts->size() != NumRegionCounters) {
     delete RegionCounts;
     RegionCounts = 0;
   }
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